Using IDT gBlocks® Gene Fragments to generate several surface zinc-finger DNA-binding domains (sZFs), this research group created cell lines that expressed these distinct domains on their surface. The scientists could then essentially barcode the different cell lines by exposing the cells to fluorophore-conjugated dsDNA in a multistep labeling approach. (Fluorophore-conjugated DNA probes were provided by IDT and contained 4 phosphorothioate bonds at both the 5’ and 3’ ends to enhance protection against nucleases prevalent in extracellular medium.) The live cells could be tracked, and also specifically isolated and enriched from within a heterogeneous cell mixture using dsDNA probes conjugated to magnetic beads or on dsDNA arrays (amine-conjugated oligonucleotides used on the arrays were provided by IDT). The researchers envision a broad range of synthetic biology applications for sZF-expressing cells including multiplex tracking of gene activity to study gene networks and pathways.